Ellipse generating turning machine



July 13, 1965 c. PIOTROWSKI ELLIPSE GENERATING TURNING MACHINE 5 Sheets-Sheet 1 Filed Dec. 27, 1965 INVENTOR.

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ELLIPSE GENERATING TURNING MACHINE INVENTOR. fix 471 6', 70294 24/32 71 a rramvz/s' July 13, 1965 Filed Dec. 27, 1963 E C. PIOTROWSKI ELLIPSE GENERATING TURNING MACHINE 5 Sheets-Sheet 3 L Y j 1 i l i E INVENTOR. [ya/471 FI'aI rau/SZ'Z.

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Jul 13, 1965 E. c. PIOTROWSKI 3,194,092

ELLIPSE GENERATING TURNING MCHINE Filed Dec. 27, 1963 5 Sheets-Sheet 4 INVENTOR. jyw4r/6T 7387 70 ws/iz' y 1955 E. c. PIOTROWSKI 3,194,092

4 ELLIPSEGENERATING TURNING MACHINE Filed Dec. 27, 1963 I 5 Sheets-Sheet 5 INVENTOR. t4 Zia/47d 6'. 7 2 02 rau/sxi United States Patent 35,194,0Q2 ELLIPSE GENERATING TURNING MAQHINE Edward C. Piotrowski, Wolverine Lake, Mich, assignor to Err-(lend) Corporation, Detroit, Mich, a corporation at Michigan Filed Dec. 27, 1%3, her. No. 333,857 ll. Claims. (Cl. 82-44) This invention relates to machines, and more particularly to adjustable turning machines such as boring machines capable of producing parts which vary in diameter along their length and may also have elliptical rather than round cross-sectional shapes along all or portions of their length.

It is an object of the invention to provide a novel and improved multiple form turning machine of this nature which is simply and easily adjustable and which will greatly reduce the cost of tooling up for the production of parts as described above, especially in small quantities such as are used for experimental purposes.

It is another object to provide an improved machine construction of this nature which is efficient and reliable in use, may be combined with the base, spindle head and other components of conventional turning machines or boring machines, and is capable of a large variety of adjustments.

Other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a partially schematic top plan View of the invention showing the main components thereof;

FIGURE 2 is an enlarged fragmentary cross-sectional plan view taken in the area marked 2 of FIGURE 1 and showing the ellipse generating ring and its associated parts;

FIGURE 3 is an end cross-sectional view the line 33 of FIGURE 2;

FIGURE 4 is a schematic showing of a typical elliptical cross section which may be created by the use of the ellipse generating ring, but in exaggerated form;

FIGURES is a cross-sectional view in elevation taken along the line 5-5 of FIGURE 1 and showing the tool holder rocker arm;

FIGURE 6 is a diagram showing different combinations of workpiece shapes which may be produced with the invention;

FIGURE 7 is a view similar to FIGURE 1 but showing a modified form of the invention in which the major axis rather than the minor axis of the workpiece cross section ellipse is fixed;

FIGURE 8 is a cross-sectional view in elevation taken along the line 86 of FIGURE 7 and showing the tool holder rocker arm; and

FIGURE 9 is a fragmentary top plan view of a further modification of the invention in which the tool holder rocker arm is mounted on a vertical rather than a horizontal pivot.

in general terms, each of the illustrated embodiments of the invention is mounted on a cross slide carried by a machine table, the table being slidable on ways in the direction of the workpiece axis, the workpiece being mounted rotatable by conventional spindle and drive equipment. The cross slide is adapted to be shifted in response to machine table movement in a direction at right angles to the direction of machine table movement by a stationary diameter control cam. An ellipse adjusting cam is mounted adjacent the diameter control cam and is adapted to follow the transverse cross slide movement but is stationary with respect to the longitudinal taken along 3,194,lli92 Patented July 13, 1965 cross slide movement as the latter travels with the machine table. The ellipse adjusting cam controls the setting of an ellipse generating ring having a round cylindrical surface, the latter in turn affecting the setting of the cutting tool during each revolution of the work.

The cutting tool is mounted on a rocker arm pivotally secured to the cross slide. The ellipse generating ring rotates on an axis parallel to the workpiece axis and at the same speed as the workpiece, a motion transfer rod connecting the ellipse generating ring with the tool holder rocker arm. The ellipse generating ring is rockable, in response to machine table travel, on an axis at right angles to its rotary axis by a connection with the ellipse adjusting came The length of stroke of the motion transfer rod during each revolution of the ellipse generating ring will be proportional to the setting of the ellipse generating ring, the reciprocal stroke length being zero when all portions of the cylindrical cam surface are concentric with the rotary cam axis and increasing as the ellipse generating ring is increasingly offset from the concentric position. The result will be that any number of combina tions of diameter and ellipticity can be selected for the workpiece shape simply by changing the shapes of the diameter control cam and ellipse adjusting cam.

Referring more particularly to the embodiment of FIGURES 1 to 6, the invention is shown as being mounted on a machine table shown partially in dot-dash lines at 11, the machine table being mounted on a bed shown partially in dot-dash lines at 12 for traverse movement in the directions of the oppositely pointing arrows 13. This direction is parallel to the axis of a workpiece shown in dot-dash lines at M which is carried by a part holding device 15 connected to a spindle is driven by belts 17 connected to a drive motor (not shown). Part 14 may i for example, be an automotive piston having grooves 13 for piston rings and a skirt extending to the left of grooves 18 in the drawing, the skirt to be machine by a cutting tool 19. It may be desired that the skirt of piston 14 have a shape which is other than a constant diameter along its axial length, for example, a slightly tapered, concave or convex shape may be desired. It may also be desired that portions of the length of the skirt, or the en tire length, have an outer cross-sectional shape which is slightly elliptical rather than round, and that the ellipticity vary along the length. Often such shapes as those described above are required for only a few parts, for example in experimental usage.

The invention is carried by a cross slide 21 which is mounted on a base 22 for feed movement perpendicular to the workpiece spindle in the directions of the oppositely pointing arrows 23 of FIGURE 1, base 22 being secured to machine table 11.

A diameter control cam 24 is stationarily secured to a component 25 of the machine which is a portion of the base or frame and is immovably connected with bed 12. Cam 24 is of elongated shape and is removably mounted in a recess 26 of a rod 2'7, one end of rod 27 being secured to machine portion 25 by a bracket 28. An

adjustable screw 29, rotatable by a member 36), may be provided for connecting rod 27 to bracket 28 in a manner permitting adjustment of the rod along its axis. A pair of guides 31 are carried by cross slide base 22 and are slidably mounted on rod 27. The surface 32 of cam 24 is shaped to correspond with the desired variation in diameter of the outer surface of workpiece 14. Cross slide 21 is provided with a cam follower 33 which is engageable with surface 32 of cam 24 when cross slide 21 is urged toward the cam. The cross slide will thus move back and forth in the direction of arrows .23 as it also moves with machine table 11 in the direction of arrows l3.

Cross slide 21 carries a bracket 34 on which is mounted a tool holder rocker arm 35 carrying cutting tool 19. Bracket $4 is adjustable toward and away from the work by an adjusting screw 36, and the pivot 37 for rocker arm 35 has an axis parallel to the workpiece spindle axis. One or more springs 38 mounted on bracket 34 constantly urge rocker arm 35 toward the workpiece, these springs being of adequate strength to permit the cutting to take place, but also permitting cutting tool 19 to be intermittently retracted and advanced during each workpiece revolution by the ellipse control means new to be described.

An ellipse adjusting cam 39 is removably mounted in a rod 40 extending parallel to rod 27 and axially adjustable in the same manner by a screw 41. The inner end of rod 4-0 carries one or more rollers 42 mounted in a track or tracks 43 secured to stationary machine portion 25, tracks 43 extending parallel to the cross slide movement 23. A pair of bearings 44 slidably supporting rod 46 are carried by cross slide 21. In other words, rod 46, and thus cam 3%, will be constrained to translatory movement in the directions of the oppositely pointed arrows 23, along with cross slide 21, but will be prevented from movement in the directions of arrows 13.

A bell crank 45 is pivoted at 46 on cross slide 21, and carries a cam follower t7 engageable with the surface 48 of cam 39. The other end of bell crank 4'5 carries an extension 49 which is connected by a coupling 50 and connect-or 51'to the outer race 52 of an anti-friction bearing 53. The inner race '4 of this hearing is secured to one end of an L-shaped member 55 which is slidably disposed within a carrier 56 for an ellipse generating ring 5'7, seen best in FIGURE 2. The unit shown in FIGURE 2 may be referred to as an ellipse generator.

Carrier 56 is secured to a spindle 58 rotatably mounted in an enclosure 59 and connected by a coupling 61 and a splined shaft 62 to a driving spindle 63 connected to spindle .16 by a timing belt 64, so that spindles 16 and 63 will rotate at the same speed. Spindle enclosure 59 is secured to cross slide 21, coupling 61 being of a universal type so as to permit the movement of spindle 59 in the direction of arrows 23 which will be imparted to it by cam 24, spindle 63 being stationarily mounted in portion 25 of the machine. Spline 62 will permit ring 57 and its associated parts to move in the direction of the arrows 13 as machine table 11 traverses bed 12.

Carrier 56 has a narrow portion 6'5 on which ring 57 is mounted by means of a cross pin 66 extending through portion 65, member 55 having an elongated clearance slot 67 through which pin 66 extends. Ring 57 has a cylindrical outer surface 68 and is carried by a mounting member 69, being secured to the mounting member by a ring 71 and bolt 72. The entire subassembly comprising members 57, 69, and 71 is of annular shape, having an inner diameter of suflicient size to permit rocking about pin 66, this pin extending at right angles to the axis of spindle 58. A spring 73 disposed within member 69 urges a pin 74 against a shoulder 75 on carrier 56, spring 73 being supported at its inner end by an adjustable member '76. Spring 73 thus urges ring 57 in one direction about pin '66. This movement is resisted by a pin 77 carried by member 55' which extends through carrier 56 and engages a pin 78 carried by member 69, pins '74 and 78 being in diametrically opposed positions. A spring '79 within the adjacent end of spindle 5G urges member 55 to the right in FIGURE 2, but as member 55 is pushed to the left in this figure by clockwise rocking of hell crank 45 in FIG- URE 2, the force of spring '79 will be counteracted and spring 73 will be permitted to rock ring 57 about pin 66. 1 In the position shown in FIGURE 2, it will be seen that an imaginary plane extending through the outer surface of ring 57 at right angles to the axis of spindle 58 will have an elliptically shaped intersection therewith, as seen in FIGURE 4. The ellipticity of this shape will be increased as ring 57 rocks counterclockwise from its FIGURE 2 position, and will be decreased as it rocks clockwise from this position, the ellipticity being Zero when ring 57 has rocked clockwise sufficiently to have all portions of surface 63 concentric with the axis of spindle 58.

A motion transfer rod 81 is slidably supported by bearings 82: carried by cross slide 21, and is adapted to transmit motion from ring 57 to rocker arm 35 which carries tool 19. More particularly, a cam follower 83 carried by rod 81 is engageable with surface "68 of ring 57 and the other end of rod 8]. is engageable with a member 84 carried by arm 35. Spring 33 will urge arm 35 and therefore rod 81 toward ring 57, so that rocker arm 35 will oscillate as the ring is rotated. Since the rate of rotation of 'ring 57 is the same as that of workpiece 14, it will thus be seen that the oscillatory motion of arm 35 will cause tool 19 to inscribe an elliptical cut on workpiece 14.

In operation, assuming that FIGURE 1 shows the parts in their starting positions, machine table 11 will be traversed to the left while workpiece 14 and ring 57 are rotated at the same speed. Cross slide 21 will gradually move upwardly because of the initial slope of surface 32 of diameter control cam 24. This will cause the mean diameter of part 14 to be tapered in a leftward direction. When follower 33 reaches the convexly shaped portion of surface 32, the mean diameter of part 14- from that point on will be similarly shaped.

At the same time, the degree to which part 14 is elliptical in cross-sectional shape will vary along its axis, as controlled by cam 39. In the first portion of travel, bell crank 45 will swing progressively counterclockwise, increasing the inclination of ring 57, so that the length of stroke of rod 81 will increase during each revolution, increasing the ellipticity of the workpiece cross section. When follower 47 reaches the portion of cam surface 48 which causes bell crank 45 to swing progressively c1ockwise, the ellipticity will decrease.

After each cut, cross slide 21 could be retracted (downwardly in FIGURE 1) by conventional cross feed elements, table 11 returned to the right, cross slide 21 returned and advanced a feed increment, and the traverse of table 11 repeated. On each cut, the cam controls for positioning tool 19 would act as described above.

' t will be noted that the actions of both cams 24 and 39 will be continuous, the position of tool 19 at any one instant being the combined result of the action of both cams and of the rotational position of ring 57. In effect, therefore, both diameter and ellipticity will be integrally combined throughout the length of the cut, forming a unique overall surface depending upon the shapes of the cams. Since earns 24 and 3? are replaceable, an infinite variety of shapes may thus be produced.

FIGURE 6 is a diagram showing a few surface combinations. In this diagram, both a circle 101 and an ellipse 162 are illustrated, being combined by a bracket 103 which points to five typical diameter variations, 104 through 108. This indicates that for any diameter variation, or a portion thereof, the cross-sectional shape may be circular or elliptical, with the ellipse having any desired ellipticity within the limits of movement of the device. Shape 104 is simply tapered, shape 105 combines a'concave profile with a cylindrical section, shape 106 is a convex profile combined with a constant diameter section, shape 107 a concave profile with a taper at one end and two cylindrical sections at the ends, and shape 1% is convex with a taper at one end thereof and two constant diameter end portions. These are of course only illustrative of the many different shapes which may be chosen.

FIGURES 7 and 8 illustrate a modified form of the invention which is basically of the same construction as the previous embodiment but in which the major axis rather than the minor axis of an elliptical workpiece cross section will be fixed. It will be noted in FIGURES 2 and 3 that those portions of cam surface 68 which are aligned with the ends of pin 66 will remain a constant distance from the axis of rotation of ring 57, regardless of the cam inclination of ring 57 as it rocks about pin 66. In the embodiment of FIGURES 1 to 6, tool 19 will be closest to the workpiece centerline as those portions of cam surface 68 which are aligned with pin 66 pass cam follower 83. This means in effect that the minor axis of an elliptical workpiece cross section will be fixed, and the major axis will vary. In many cases, however, the major axis of the cross section is the more critical dimension, and should be held to closer tolerances than the minor axis.

In the embodiment of FIGURES 7 and 8, bracket 34 and tool holder rocker arm 35 are replaced by a bracket 34 and a tool holder rocker arm 35' pivoted at 37 to bracket 34 and carrying a cutting tool 19'. Bracket 34' and rocker arm 35 are mounted on the side of workpiece 14 opposite that on which bracket 34 and tool holder rocker arm 35 were mounted. A motion transfer rod 81' is slidably supported by bearings 82' and transmits motion from ellipse generating ring 57 to arm 35', the latter being urged against rod 31' by a tension spring 38'.

The operation of the embodiment of FIGURES 7 and 8 will be the same as that of FIGURES 1 to 6, except that tool 1 will be at the major axis of an elliptical workpiece cross section each time those portions of cam surface 68 which are aligned with pin 66 come into contact with cam follower 33 on rod 81'. This is because tool 19' will be urged toward the axis of rotation of workpiece 14 as the wider parts of ring 57 come into contact with follower 83, and will be withdrawn from the workpiece axis as the narrower parts of ring 57 approach follower 83'. Of course, if ring 57 is not inclined by being rocked about pin 66, tool 19 will not move toward or away from the workpiece axis as ring 57 rotates.

FIGURE 9 illustrates a third embodiment of the invention which, like the embodiment of FIGURES 7 and 8, has the effect of creating a fixed major axis for an elliptical workpiece cross section and varying the minor axis. In this case, the eifect is accomplished by having a tool holder rocker arm 35" which is on the same side of the workpiece (not shown in FIGURE 9) as rocker arm 35 of the embodiment of FIGURES 1 to 6, but which is mounted on a vertical pivot 37" carried by a bracket 34" secured to cross slide 21. One end of arm 35 carries a follower 84" which is engageable by motion transfer rod 81", the latter being carried by bearings 82" mounted on the cross slide. Tool 19" is. secured to the other end of rocker arm 35", this end of the rocker arm being urged away from the workpiece by a tension spring 38".

In operation of the embodiment of FIGURE 9, it will be seen that, because of the lever action of arm 35", motion of rod 81 will have exactly the opposite effect as that of rod 81 in the embodiment of FIGURES 1 to 6. Thus, those portions of cam surface 68 which are aligned with pin 66 and are therefore a fixed distance away from the rotational axis of ring 57 will determine the major axis of an elliptical workpiece cross section.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In a multiple form turning machine, a workpiece spindle, a bed, a table mounted for traverse movement on said bed parallel to the workpiece spindle, a cross slide on said table mounted for feed movement perpendicular to the workpiece spindle, a tool mounted on said cross slide for movement with respect to the cross slide perpendicular to the work piece spindle, a stationary diameter control cam, a cam follower on said cross slide engageable with said diameter control cam, the diameter control cam controlling said feed movement of the cross slide in response to traverse movement of the table, an ellipse generating ring rotatably mounted on said cross slide on an axis parallel to the workpiece spindle and having a surface of revolution, means for rotating the ellipse generating ring in timed relation with said workpiece spindle, means for rockably adjusting said ellipse generating ring on an axis perpendicular to its rotational axis, and motion transmitting means connecting said ellipse generating ring with said tool. i

2. The combination according to claim 1, said means for rockably adjusting said ellipse generating ring compris ing an ellipse adjusting cam carried by said cross slide for feed movement therewith, means preventing traverse movement of said ellipse adjusting cam, and means connecting said ellipse adjusting cam and said ellipse generating ring and responsive to traverse movement of said table and cross slide for rocking said ellipse generating ring about said axis perpendicular to its rotational axis as controlled by the shape of said ellipse adjusting cam.

3. In a multiple form turning machine, a workpiece spindle, a bed, a table mounted for traverse movement on said bed parallel to the workpiece spindle, a. cross slide on said table mounted for feed movement perpendicular to the workpiece spindle, a rocker arm carried by said cross slide and rockable on an axis carried thereby, a tool secured to said rocker arm, a stationary diameter control cam, a cam follower on said cross slide engageable with said diameter control cam, the diameter control cam controlling said feed movement of the cross slide in response to traverse movement of the table, an ellipse generating ring rotatably mounted on said cross slide on an axis parallel to the workpiece spindle and having a surface of revolution, means for rotating said ellipse generating ring in timed relation with said workpiece spindle, means for rockably adjusting said ellipse generating ring on an axis perpendicular to its rotational axis, and motion transmitting means connecting said ellipse generating ring with said tool rocker arm.

4. The combination according to claim 3, the rocking axis of said rocker arm being parallel to said workpiece spindle.

5. The combination according to claim 4, said rocker arm and tool being on the side of said workpiece spindle remote from said ellipse generating ring, whereby those portions of the ellipse generating ring which are a constant distance from its rotational axis will define the minor diameter of an elliptical workpiece cross section.

6. The combination according to claim 4, said rocker arm and tool being on the same side of said workpiece spindle as said ellipse generating ring, whereby those portions of the ellipse generating ring which are a constant distance from its rotational axis will define the major axis of an elliptical workpiece cross section.

'7. The combination according to claim 3, the rocking axis of said rocker arm being on the side of said workpiece spindle remote from said ellipse generating ring and being perpendicular to said workpiece spindle, the rocker arm axis being at an intermediate portion of said rocker arm, said motion transmitting means being connected to one end of said rocker arm, and said tool being secured to the other end or" said rocker arm, whereby the portions of said ellipse generating ring which are a constant distance from its rotational axis will define the major diameter of an elliptical workpiece cross section.

8. In a multiple form turning machine, a workpiece spindle, a bed, a table mounted for traverse movement on said bed parallel to the workpiece spindle, a cross slide on said table mounted for feed movement perpendicular to the workpiece spindle, a rocker arm carried by said cross slide and rockable on an axis parallel to said workpiece spindle, a tool secured to said rocker arm, a stationary diameter control cam, a cam follower on said cross slide engageable with said diameter control cam, the diameter control cam controlling said feed movement of the cross slide in response to traverse movement of the table, an ellipse generating ring rotatably mounted on said cross slide on an axis parallel to the workpiece spindle and having a surface of revolution, means for rotating said ellipse generating ring in timed relation with said workpiece spindle, means for rockably supporting said ellipse generating ring on an axis perpendicular to its rotational axis, an ellipse adjusting cam carried by said cross slide for feed movement therewith, means preventing traverse movement of said ellipse adjusting cam, means connecting said ellipse adjusting cam and said ellipse generating ring and responsive to traverse movement of said table and cross slide for rocking said ellipse generating ring about said axis perpendicular to its rotational axis as controlled by the shape of said ellipse adjusting cam, and motion transmitting means for connecting said ellipse generating ring with said tool.

9. The combination according to claim 8, said motion transmitting means comprising a motion transfer rod slidably mounted on said cross slide for movement perpendicular to the workpiece spindle and connecting said ellipse generating ring and said rocker arm.

10. In a multiple form turning machine, a workpiece spindle, a bed, a table slidably mounted on said bed for movement parallel to the workpiece spindle, a cross slide mounted on said table for feed movement perpendicular to said workpiece spindle, a first elongated cam holder fixed to said bed and extending parallel to said workpiece spindle, a diameter control cam removably mounted on said first cam holder, a cam follower on said cross slide responsive to traverse movement of said table for adjusting the feed position of said cross slide as controlled by the shape of said diameter control cam, a tool supporting arm movably mounted on said cross slide for movement perpendicular to the workpiece spindle, a tool carried by said supporting arm, a spring urging said supporting arm in a direction causing said tool to engage a workpiece supported by said workpiece spindle, a second elongated cam holder slidably mounted on said cross slide and extending in a direction parallel to the workpiece spindle, means restraining said second cam holder against movement with respect to said bed in a direction parallel to said workpiece spindle but permitting said second cam holder to move with said cross slide perpendicular to the workpiece spindle, an ellipse adjusting cam carried by said second cam holder, an ellipse generating ring spindle carried by said cross slide for rotation on an axis parallel to the workpiece spindle, a timing drive beween said workpiece and ellipse generating ring spindles for causing said ellipse generating ring spindle to rotate at the same rate of speed as said workpiece spindle, means connecting said last-mentioned drive to said ellipse generating ring spindle in a manner which permits the ellipse generating ring spindle to have traverse and feed movements with respect to said bed, an ellipse generating ring having a cylindrical outer surface and secured to said ellipse generating ring spindle for rotation therewith, a pivotal connection between said ellipse generating ring and ellipse generating ring spindle for permitting said ellipse generating ring to rock on an axis perpendicular to the axis of the ellipse generating ring spindle, a linkage between said ellipse adjusting cam and ellipse generating ring for controlling said last-mentioned rocking movement in accordance with the shape of said ellipse adjusting cam, and a motion transfer rod slidably mounted on said cross slide for movement perpendicular to said workpiece spindle, one end of said rod having a cam follower slidably engageable with said ellipse generating ring and the other end being connected to said tool support arm.

11. The combination according to claim 6, said linkage comprising a bell crank pivotally mounted on said cross slide and having one arm engageable with said ellipse adjusting cam, a spring urging said ellipse generating ring in one direction about said pivotal connection with its spindle, and a member slidable coaxially with said ellipse generating ring spindle, said member being connected at one end to the other arm of said bell cank and at the other end to said ellipse generating ring at a point diametrically opposite said last-mentioned spring.

No references cited.

WILLIAM W. DYER, 111., Primary Examiner. 

1. IN A MULTIPLE FORM TURNING MACHINE, A WORKPIECE SPINDLE, A BED, A TABLE MOUNTED FOR TRANSVERSE MOVEMENT ON SAID BED PARALLEL TO THE WORKPIECE SPINDLE, A CROSS SLIDE ON SAID TABLE MOUNTED FOR FEED MOVEMENT PERPENDICULAR TO THE WORKPIECE SPINDLE, A TOOL MOUNTED ON SAID CROSS SLIDE FOR MOVEMENT WITH RESPECT TO THE CROSS SLIDE PERPENDICULAR TO THE WORK PIECE SPINDLE, A STATIONARY DIAMETER CONTROL CAM, A CAM FOLLOWER ON SAID CROSS SLIDE ENGAGEABLE WITH SAID DIAMETER CONTROL CAM, THE DIAMETER CONTROL CAM CONTROLLING SAID FEED MOVEMENT OF THE CROSS SLIDE IN RESPONSE TO TRAVERSE MOVEMENT OF THE TABLE, AN ELLIPSE GENERATING RING ROTATABLY MOUNTED ON SAID CROSS SLIDE ON AN AXIS PARALLEL TO THE WORKPIECE SPINDLE AND HAVING A SURFACE OF REVOLUTION, MEANS FOR ROTATING THE ELLIPSE GENERATING RING IN TIMED RELATION WITH SAID WORKPIECE SPINDLE, MEANS FOR ROCKABLY ADJUSTING SAID ELLIPSE GENERATING RING ON AN AXIS PERPENDICULAR TO ITS ROTATIONAL AXIS, AND MOTION TRANSMITTING MEANS CONNECTING SAID ELLIPSE GENERATING RING WITH SAID TOOL. 